Atomic layer deposition of iridium thin films and their application in gold electrodeposition

Abstract

Advances in the deposition of metallic thin films are discussed. The ALD growth of ultrathin Ir films is analyzed by transmission electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, and optical and electrical measurements. The morphology of iridium metallic layers is assessed based on Ir/ Al2O3 nanolaminate films. High resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements show sharp interfaces and pure Ir layers in the nanolaminates. The iridium films as polycrystalline. Excellent thickness control, high uniformity and low roughness of ALD films are demonstrated. Four point probe measurements of the resistivity of Ir coatings with various thicknesses have been performed and proved conductive layers with an Ir film thickness of ca. 10 nm. The optical properties of the Ir films deposited by ALD are similar to those of the bulk Ir. Thin iridum layers deposited on high aspect ratio linear gratings have been successfully used as electrodes in the electrochemical deposition of gold nanoparticles and gold layers. The gold deposition evolves through the formation of gold islands with ca. 40 nm diameters that coalesce after ca. 60 seconds deposition. The density of the gold islands within the grating pattern is much lower than on the flat region of the substrate. The combination of ALD with electrochemical deposition allows the diversification of conductive layers on complex nanostructured surfaces

Nucleation and Conformality of Iridium and Iridium Oxide Thin Films Grown by Atomic Layer Deposition

“…After 500 cycles, all the films seemed to cover the substrate completely, which means that a dense, hole-free film was formed in the thickness range of 5 to 15 nm; possibly quite close to 5 nm, considering that at this thickness the films were already conductive. Previously reported minimum thicknesses for iridium films covering Al 2 O 3 substrate are 9 nm using the Ir­(acac) 3 + air process at 300 °C, 6 nm using the Ir­(acac) 3 + O 2 process at 350 °C, and 7 nm using the Ir­(acac) 3 + O 3 + H 2 process at 185 °C . We are not aware of such reports for iridium oxide.…”

Perylenes, Porphyrins, and Other Large Dye Molecules for Molecular Layer Deposition

“…[2] This allows use of more delicate substrates like fabrics and other fragile organic based materials. The low temperature also prevents most bulk diffusion processes in the deposited materials, allowing multilayers of different materials on nanometer [3] and even sub-nanometer level [4,5] . The sequential introduction of precursors on the other hand allows combinations of very reactive precursors without undesired reactions.…”

Single-step approach to sensitized luminescence through bulk-embedded organics in crystalline fluorides

“…In the recent years, several different combinations of material classes have been synthesized as nanocomposites by ALD. This includes multiple different oxides 27,28 , oxide-nitride 29 , oxide-sulfide 30 , oxide-metal 31,32 , oxide-hybrid 33 , and even controlled crystalline oxide-amorphous oxide 34 nanocomposites. Several of these are used to control optical properties 30,34 or in optics 31 .…”